Insulating plates capable of being bonded are known. Examples of these plates are heat-insulating plates having a glass-fibre covering or an adhesive film coating. Such plates generally have good heat-insulating properties but, for many uses, they do not have sufficient thermal stability.
Ceramic plates which are capable of being bonded and are resistant to high temperatures are known. However, they generally have poor heat-insulating properties.
In general, insulating plates that are formed by pressing a highly disperse inorganic heat-insulating material without a binder have heat insulating properties similar to the properties of the heat-insulating material. In practice, however, plates of this type must be considered as not bondable since the areas of adhesion loosen under slight mechanical strain.
Shaped articles, including plates, comprising a highly disperse inorganic heat-insulating material and a binder homogeneously distributed within the article are also known. In order to provide shaped articles of this type, with a surface capable of being bonded, large quantities of binder have to be incorporated into the article. The large quantities of binder required increases the conductivity of the article and reduces the heat-insulating properties to unacceptably low levels.
The present invention provides an insulating plate which is capable of being bonded, which can withstand the strain of relatively high temperatures and which has heat insulating properties similar to binder-free heat-insulating plates.
The invention provides an insulating plate that can be used as a cooking plate, which can withstand the temperature strain of a red-hot wire heating element adhered thereto by a mechanically strong and stable bond. The insulating plate of the present invention has an overall thickness about the same as the thickness of a binder-free plate having the same insulating value.